This invention relates to an apparatus for separating slack-filled capsules from properly filled capsules having the same surface area.
In manufacturing capsules, particularly capsules for medicinal purposes, it is necessary that each capsule contain the proper amount of material such as medicament. With some capsules such as those containing vitamins which are used over a long period, primarily for preventive rather than for therapeutic purposes, a single slack-filled capsule is not too serious. With capsules containing antibiotics or analgesics and many other therapeutic agents, the contents of a single capsule are relied upon to do a particular job at a particular time, and it is therefore necessary that each capsule contain the desired quantity of medicine.
Any filling operation for the filling of capsules can go wrong, even though highly reliable apparatus and processes are used so that the number of defects is a small fraction. Nonetheless, it is necessary or desirable that the defective capsules, no matter how small their percentage, be selected and rejected. In many instances, the capsules are opaque so that a visual inspection cannot be used. Some other method of eliminating defectively filled capsules is therefore necessary.
Medical capsules are usually either hard shell capsules, in which two pre-formed parts of the capsule are telescoped together to contain the filled material, or soft shell capsules which are formed from strips of soft plastic such as gelatin, with water and plasticizers. The wall thickness are uniform, hence any variation in weight in indicative of an improperly filled capsule. The size of the capsule is usually chosen so that it is impossible to overfill the capsule because it is desired that the maximum contents be placed in the capsule so that the capsule is as small and easily swallowed as possible. The individual weighing of the filled capsules on a sufficiently sensitive scale or balance would give an adequate check; but individual weighing is too expensive and time-consuming to be used in production quantities, if other apparatus and processes can be devised.
The use of machines to separate slack-filled capsules from properly filled capsules have tended to be by weighing the capsules, or by using a sorting device which requires a separate operation during encapsulation. For example, an electronic balance and a centrifuge have been used, respectively, to weigh and to separate capsules.
Applicants are not aware of any prior art reference which, in their respective judgments as one skilled in the apparatus of the instant invention would anticipate or render obvious the apparatus; however, for the purpose of fully developing the background of the invention and establishing the state of the requisite art, the following references are set forth.
U.S. Pat. No. 3,097,161 discloses an apparatus for separating improperly filled capsules by blowing air upwardly through air jets. The capsule profile is moved randomly over the air jets;
And U.S. Pat. Nos. 1,792,962; 1,262,559; and 1,003,138 which disclose generally the use of lateral air flow to separate respectively, oversize materials, and chaff from bean and pea, and from coffee.
The empty capsule ejector of this invention has advantages over the prior art. The empty capsule ejector of this invention can be used online with a continuous encapsulation process. Therefore, the need for additional production for capsule separation is minimized or eliminated. Also, the largest cross-sectional area of the capsule profile is exposed to the laminar air flow of this invention. This results in a more precise control of weight variation, which is of extreme importance where the only variance is capsule weight.
The usefulness of this apparatus for separating slack-filled capsules from properly filled capsules is in the use and control of laminar air flow. The adjustment of the laminar air flow to reduce the turbulence between the point of contact with the capsule profile and the forced air source can be regulated by one or a series of dampers. This adjustment is critical and will vary for capsules with different size and with different medicament powder weight. This apparatus is useful to separate hard shell and soft shell capsules.